The present disclosure relates to ink compositions containing an additive and printing processes. More specifically, the present invention relates to aqueous ink compositions comprising a water-compatible or ink-compatible anti-intercolor bleed agent. The inks typically comprise at least water and a colorant of a dye or a pigment or a mixture of dye and pigment. In one embodiment the anti-intercolor bleed agent of the invention comprises a glycine material, particularly fluorinated glycine composition, more particularly a fluoroalkyl glycine salt with high fluorine content. The ink jet ink compositions of the present invention are particularly suitable for ink jet printing processes.
Ink jet printing is a non-impact printing method that produces droplets of ink that are deposited on a substrate such as paper or transparent film in response to an electronic digital signal. Non-impact printing methods (systems) include drop-on-demand ink jet printing and continuous-stream ink jet printing. Drop-on-demand ink jet printing processes include thermal ink jet printing processes, acoustic ink jet printing processes, and piezoelectric ink jet printing processes. Thermal or bubble jet drop-on-demand ink jet printers and piezoelectric ink jet printers have found broad application as output for personal computers in the office and in the home.
In existing thermal ink jet printing processes, the printhead typically comprises one or more ink jet ejectors, each ejector including a channel communicating with an ink supply chamber, or manifold, at one end and having an opening at the opposite end, referred to as a nozzle. A thermal energy generator, usually a resistor, is located in each of the channels, at a predetermined distance from the nozzles. The resistors are individually addressed with a current pulse to momentarily vaporize the ink within the respective channel to form a bubble that expels an ink droplet. As the bubble grows, the ink rapidly bulges from the nozzle and is momentarily contained by the surface tension of the ink as a meniscus. This is a very temporary phenomenon, and the ink is quickly propelled toward a print substrate. As the bubble begins to collapse, the ink still in the channel between the nozzle and bubble starts to move towards the collapsing bubble, causing a volumetric contraction of the ink at the nozzle and resulting in the separation of the bulging ink from the nozzle as a droplet. The acceleration of the ink out of the nozzle while the bubble is growing provides the momentum and velocity for propelling the droplet in a substantially straight line direction towards a print substrate, such as a piece of paper or transparency. Because the droplet of ink is emitted only when the resistor is actuated, this type of thermal ink jet printing is known as "drop-on-demand" printing. Other types of drop-on-demand ink jet printing include piezoelectric and acoustic ink jet printing. Several drop-on demand ink jet printing processes are described in U.S. Pat. Nos. 5,281,261, 5,693,129, and No. 5,851,274, the disclosures of which are totally incorporated herein by reference.
Continuous-stream ink jet printing is known to print on a substrate by placing ink droplets at desired locations while deflecting ink droplets away from the non-imaging areas. This type of ink jet printing is different from the drop-on-demand method, and is also described in, e.g., U.S. Pat. No. 5,281,261, the disclosure of which is totally incorporated herein by reference.
In an ink jet printing apparatus, the printhead typically comprises a linear array of ejectors. However, for faster ink jet printing, several printheads may be butted together to form a partial-width printhead. The printhead or partial-width printhead is moved relative to the surface of the print substrate, either by moving the print substrate relative to a stationary printhead, or vice-versa, or both. In some types of apparatus, a relatively small printhead moves across a print substrate numerous times in swathes, in order to complete a desired image. A partial image is created with each swath of the printhead movement. This type of ink jet printing is called multi-pass or checkerboard printing process. Ink jet printing processes using the partial-width printhead and checkerboard printing process can improve printing speed and productivity and such processes are incorporated in our invention. Ink jet printers employing the partial-width printhead are called "partial-width" printers.
Alternatively, a printhead (e.g., a full-width printhead or printbar comprising several butted printheads) that consists of an array of ejectors and extends the full width (or any desired length) of the print substrate may be held stationary. An ink may be deposited onto the print substrate one line at a time by the full-width printhead (or partial-width printhead covering a portion of the width of a substrate) as the print substrate passes by, until full-page images are completed. This type of ink jet printing process uses a single pass method and it is carried out in what is usually known as a "full-width array" or "partial-width" printer. When the full-width or partial-width printhead and the print substrate are moved relative to each other, image-wise digital data is used to selectively activate the thermal energy generators in the printhead over time so that the desired image will be created on the print substrate. In a multi-color ink jet printing process several full-width or partial-width printheads are used in a printer to deposit different color inks (e.g., black, cyan, magenta, and yellow inks, as well as other optionally selected inks) onto a print substrate to give full color images. In this so-called "single pass method" the printheads are usually held stationary while the imaging substrate moves by (or move under) the printheads. This type of single pass method often employs the full-width array printheads and different color inks to achieve high-speed ink jet printing for the production of multi-color images on a substrate.
Aqueous inks used in ink jet printing generally have water as a major component. Water has the advantage of being non-toxic, non-combustible and environmentally sound relative to non-aqueous inks, which are largely composed of organic solvents. Water is also an excellent medium for dispersing pigments or dissolving dyes. Water is also used for bubble formation and a propellant for the ink in a thermal ink jet printing process.
In a multi-color ink jet printing process, a phenomenon known as "inter-color bleed" may occur. This effect is described in, e.g., U.S. Pat. No. 5,371,531, the disclosure of which is totally incorporated herein by reference. This phenomenon is the bleed of an ink into another ink of different color resulting in mixing one color portion of the image into another portion of the neighboring image of a different color. This becomes most apparent when a black ink is imaged immediately adjacent to an area printed with a color ink such as cyan, magenta or yellow ink. In such a case, the black ink (usually a slow or medium dry ink which usually exhibits good edges for text and high optical density) will be seen to bleed into the color area or vice versa to create a conspicuous print defect which is called intercolor bleed. In some cases the black ink may generally possess high surface tension, while the color inks are generally fast dry inks with low surface tension. Intercolor bleed can take place quickly once the inks are printed a substrate, e.g., on plain paper or transparency or textile before drying (e.g., before microwave or radiant heating or drying at room temperature). For example, printing a slow dry black ink immediately followed by a color ink (especially a yellow ink before the black ink can completely dry) can show undesired inter-color bleed phenomenon with poor print quality. The intercolor bleed between a black ink and a neighboring yellow ink is especially sensitive to human eyes due to high color contrast. Intercolor bleed between the black ink and cyan or magenta ink as well as the intercolor bleed between two different color inks (e.g. cyan yellow, cyan and magenta, magenta and yellow, etc.) also give poor image quality that is not desirable.